U.S Rep. Justin Amash, a Republican congressman from Michigan says he’s concluded that President Donald Trump has “engaged in impeachable conduct.” Congressman Justin Amash tweeted Saturday that he has read the entire redacted version of special counsel Robert Mueller’s Russia report.

WASHINGTON — Justin Amash finally said out loud what many other Republicans know but will only whisper: “President Trump engaged in specific actions and a pattern of behavior that meet the threshold for impeachment.” Amash’s party may never forgive him. His nation ought to thank him.

The Michigan congressman on Saturday became the first significant GOP official to acknowledge the clear implication of special counsel Robert Mueller’s report. Every Republican member of Congress should be pressed for an on-the-record response. How does the president’s conduct not amount to obstruction of justice? Where does the Constitution give Congress the right not to act?

Democrats should be asked these questions, too. I understand that many, apparently including House Speaker Nancy Pelosi, believe that starting impeachment proceedings would damage the party’s prospects in the 2020 election. But isn’t duty supposed to take precedence over political expediency? It clearly did for Amash, whose reward for his principled stance was a Twitter blast from Trump and a primary challenge for his seat.

Classy as ever, Trump called Amash a “total lightweight” and a “loser who sadly plays right into our opponents [sic] hands!” All the president accomplished with this name-calling was to give Amash’s analysis a much wider hearing.

Amash wrote in a series of tweets that he reached his conclusion “only after having read Mueller’s redacted report carefully and completely, having read or watched pertinent statements and testimony, and having discussed this matter with my staff, who thoroughly reviewed materials and provided me with further analysis.”

That sounds like the sort of thing we pay elected officials and their staff members to do. But Amash wrote that few of his colleagues “even read Mueller’s report; their minds were made up based on partisan affiliation.”

That’s actually a key point. Anyone who reads the 448-page report can see, as Amash concludes, that Attorney General William Barr — in his four-page summary, his congressional testimony and other statements — “intended to mislead the public” about Mueller’s findings. Barr apparently “hopes people will not notice,” his deception, Amash says. Busted.

Amash’s emperor’s-new-clothes moment did not cause the dam of blind GOP solidarity to break. Instead, his colleagues attacked him, with House Minority Leader Kevin McCarthy, R-Calif., saying that maybe Amash “wants some type of exit strategy.” In other words, apparently, carefully reading the Mueller report and thoughtfully analyzing its findings means you’re no longer welcome in today’s Republican Party and might as well leave.

As McCarthy noted, this is not the first time that Amash has been inconveniently faithful to his principles. I disagree with many of Amash’s libertarian views, but it is refreshing to see a politician stand up for what he believes.

In the Mueller report, Amash finds “multiple examples of conduct satisfying all the elements of obstruction of justice.” Impeachment, Amash notes, “does not even require probable cause that a crime … has been committed,” but simply that an official “has engaged in careless, abusive, corrupt or otherwise dishonorable conduct.” Trump does all of the above, all of the time.

I’m under no illusions here. At this point it is clear that the vast majority of congressional Republicans will stay aboard the rustbucket USS Trump, which has been taking on water from the beginning, until it actually begins to sink.

But here is a line from Amash’s tweetstorm that Democrats should reflect on: “While impeachment should be undertaken only in extraordinary circumstances, the risk we face in an environment of extreme partisanship is not that Congress will employ it as a remedy too often but rather that Congress will employ it so rarely that it cannot deter misconduct.”

Speaking of misconduct, the Trump administration is now refusing to comply with perfectly lawful subpoenas issued by duly constituted committees of the U.S. Congress. If this president is allowed to get away with such defiance, why wouldn’t the next president do the same — or go even further? What good is a system of checks and balances if officials decline to use the tools that the framers of the Constitution so painstakingly crafted?

I can’t be certain what the political impact of a formal impeachment process might be. Trump would doubtless claim he was being persecuted, as a way to rile up his base and boost GOP turnout. But he will surely claim victimhood anyway, even if Pelosi decides not to move forward. Bullies cannot be appeased. They must be confronted.

Democrats’ options for avoiding impeachment are narrowing. Amash’s politically dangerous stand is a reminder that elected officials, regardless of party, are supposed to put duty first.